How hominids heard.

Ancient South African hominids that lived between 2.5 million and 1.5 million years ago could have heard high-frequency consonants better than either chimps or modern humans. An ability to hear, and presumably make, these sounds might have made these species more competitive, Bruce Bower wrote in "Ancient hominid ears were tuned to high frequencies" (SN: 10/31/15, p. 17).

Such communications would not have required a language like that of modern humans, Bower wrote, but simply vowel and consonant sounds with shared meanings. Reader Mike Kobrick wanted to know what distinguishes a language. "If vowel and consonant sounds with shared meanings isn't language, then what is?" he asked in an e-mail.

There's a big difference between sound combinations with shared meanings, such as warning or mating calls, and a grammatical language with words that can be combined in a multitude of ways to express all sorts of ideas, Bower says. Scientists consider the use of a complex grammatical structure a trait that separates humans from other animals. For decades, scientists have been debating how early hominids communicated. Unfortunately language, like social behavior, doesn't fossilize, Bower notes.